1. Field of the Invention
The present invention relates to a navigation system, or, more particularly, to a navigation system capable of presenting point information associated with data of broadcast contents and a map data display method.
2. Description of the Related Art
Navigation systems can detect the position of an own vehicle and the traveling speed thereof in real time by utilizing the global positioning system (GPS). A map is displayed on a display unit according to digitized map data. A current position measured by the GPS, a recommended route to a destination along which a user is guided to the destination, or the like is displayed while being superimposed on the display map.
The navigation system can present marks, which represent various landmarks, such as fast-food restaurants, convenience stores, family restaurants, and event halls, while superimposing them on a map displayed on a display unit on the basis of point information (hereinafter the marks displayed on the display unit shall be called landmarks). As for the display of the landmarks, what category should be displayed or not displayed can be designated by selecting a menu item from any of hierarchically structured menus displayed on the display device.
As mentioned above, landmarks can be superimposed on a map presented by a navigation system. In a conventional navigation system, landmarks existent in a portion of a map displayed on the display unit are merely displayed based on point information.
Incidentally, on-vehicle equipment includes a broadcast receiver having the ability to receive programs broadcast from television or radio broadcasting stations. A commercial message (CM) is inserted between broadcast programs. Assume that a CM is broadcast while a user who may be a driver or a passenger in a compartment is watching or listening to a program presented by the broadcast receiver.
For example, the CM is a CM concerning a fast-food restaurant. The user may want to stop at the fast-food restaurant. In this case, the user uses the navigation system to search the nearest fast-foot restaurant on the basis of a displayed region (current point). The user then designates the fast-food restaurant displayed as the result of the search and searches for a route to the fast-food restaurant by himself or herself.
As mentioned above, when a specific landmark is designated from among displayed landmarks or a new landmark is searched, an action must be performed on the navigation system. Consequently, the navigation system must be operated. It is a nuisance to operate the navigation system for a search every time a user gets interested in a program or a CM that is broadcast from time to time. Besides, it is dangerous to operate the navigation system during driving.